Correct Option
The correct option isSugar
Explanation
Pure distilled water is a poor conductor of electricity because it lacks free charge carriers. For an aqueous solution to conduct electricity significantly, the dissolved substance must dissociate into free-moving ions (cations and anions). Substances that produce ions in solution are called electrolytes, while those that dissolve as neutral molecules are non-electrolytes.
Option Analysis
- Common salt Common salt (NaCl): This is an ionic compound. When dissolved in water, it dissociates completely into sodium ions (Na+) and chloride ions (Cl-). These free ions act as charge carriers, significantly increasing electrical conductivity.
- Sugar (Sucrose): Sugar is a covalent compound. When dissolved in water, it separates into individual neutral molecules but does not dissociate into ions. Due to the absence of free charge carriers, the solution does not conduct electricity significantly.
- Lemon juice Lemon juice: Lemon juice contains citric acid. Acids dissociate in water to release hydrogen ions (H+) and corresponding anions. The presence of these ions allows the solution to conduct electricity.
- Caustic soda Caustic soda (NaOH): Sodium hydroxide is a strong base and a strong electrolyte. It dissociates completely into sodium ions (Na+) and hydroxide ions (OH-), resulting in high electrical conductivity.
Key Takeaway
Electrical conductivity in aqueous solutions depends on the presence of free ions. Electrolytes (salts, acids, and bases) dissociate to provide these ions, whereas non-electrolytes (like sugar or alcohol) do not significantly alter the conductivity of distilled water.